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Vertical
The vertical–horizontal illusion is the tendency for observers to overestimate the length of a vertical line relative to a horizontal line of the same length. This involves a bisecting component that causes the bisecting line to appear longer than the line that is bisected. People often overestimate or underestimate the length of the bisecting line relative to the bisected line of the same length.de Montalembert, M., & Mamassian, P. (2010). The Vertical–Horizontal Illusion in Hemi-Spatial Neglect. Neuropsychologia, 48(11), 3245-3251. . This even happens if people are aware that the lines are of the same length. Cross-cultural differences in susceptibility to the vertical–horizontal illusion have been noted. People from Western cultures and people living in urban landscapes show more susceptibility than those living in eastern or open landscapes.Shiraev, E., & Levy, D. (2007). Cross-Cultural Psychology, Third Edition. Pearson Education, Inc., page 110 Types of vertical–horizontal illusions There are several different configurations of the vertical–horizontal illusion. The three configurations which seem to produce the highest illusion magnitude are the L configuration, the plus (+) configuration, and the inverted-T configuration. Of these three, the inverted-T configuration produces the highest illusion magnitude. When the bisecting line of the T illusion is configured horizontally, the illusion magnitude is lowered. However, when the bisecting line of the T illusion is configured vertically, the illusion magnitude is higher.Wolfe, U., Maloney, L.T., & Tam, M. (2005). Distortions of perceived length in the frontoparallel plane: Tests of perspective theories. Perception & Psychophysics, 67(6), 967-979. Development A gradual decrease in error of vertical–horizontal illusions occur as participants age increases from eight to fourteen years.Winch, W.H. (1907). The Vertical-Horizontal Illusion in School Children. British Journal of Psychology II, 220-225. Gough and Meschieri attribute this decrease in error to the child's improved ability to detect and de-center their attention in a visual display, i.e. position their body differently to gain other pererspectives.Gough, Harrison & Meschieri, Luigi (1971). Cross-Cultural Study of Age-Related Differences in Perceptual Acuity. Journal of Consulting and Clinical Psychology, 37(1), 135-140. Children who showed greater personal independence, verbal articulation, and visual scanning ability were more effective and resourceful in their ability to gauge vertical–horizontal illusions.Gough, Harrison & Meschieri, Luigi (1971). Cross-Cultural Study of Age-Related Differences in Perceptual Acuity. Journal of Consulting and Clinical Psychology, 37(1), 135-140. Cross-cultural differences Cross-cultural differences in susceptibility to the vertical–horizontal illusion have been noted in several studies. People living in developed urban cities show greater susceptibility than people living in rural areas.Mast, F.W., & Oman, C.M. (2004). Top-Down Processing and Visual Reorientation Illusions in a Virtual Reality Environment. Swiss Journal of Psychology/Schweizerische Zeitschrift Für Psychologie/Revue Suisse De Psychologie, 63(3), 143-149. . An explanation could be that those in rural areas are more accustomed to living in round houses on flat plains, or scrubland. Rural inhabitants have more exposure to distance and living on plains than people living in highly developed, commercialized cultures.Robinson, J.O. (1972). The Psychology of Visual Illusion. Oxford, England: Hutchinson University Library. Hemispheric neglect Participants with hemispatial neglect had increased difficulty perceiving the equality of the lines on the vertical–horizontal illusion, in comparison with those in the control group. Montalembert's study, among others, gives claim to the notion that we perceive these types of illusions utilizing the left hemisphere of our brain.Rasmjou, S., Hausmann, M., & Güntürkün, O. (1999). Hemispheric Dominance and Gender in the Perception of an Illusion. Neuropsychologia, 37(9), 1041-1047. . Gender differences Gender differences have been found with regards to vertical–horizontal illusions. Rasmjou's 1998 study found men to outperform women in perceiving the vertical–horizontal illusion. The results of this variation could be from hemispheric asymmetries, and/or biological differences between men's and women's brains.Rasmjou, S., Hausmann, M., & Güntürkün, O. (1999). Hemispheric Dominance and Gender in the Perception of an Illusion. Neuropsychologia, 37(9), 1041-1047. . Although women were found to have a higher illusion magnitude on vertical–horizontal illusion tasks, this does not mean men are better judges of distance than women, as there has been minimal research on this topic. Additional research is needed to draw a significant relationship between illusion magnitude and real-world tasks. These differences could also be due to social learning differences between men and women. Functional applications Functional applications of vertical–horizontal illusion exist. Elliot et al. studied the effects of the horizontal and vertical illusion, and how the perceived illusion can influence visuo-motor coordination, i.e. motor activity dependent on sight.Elliott, D.B., Vale, A., Whitaker, D., & Buckley J.G. (2009). Does My Step Look Big In This? A Visual Illusion Leads To Safer Stepping Behaviour. PLoS ONE 4(2): e4577. . The study specifically focused on how the perceived height of a step, manipulated by the vertical and horizontal illusion, influenced stepping strategy as shown in toe elevation during step clearance. Their results showed an increased toe elevation in conditions where an illusion was perceived, leading them to conclude that there was a correlation between visual illusion and visuo-motor coordination. This can be implemented in the real world by developing better safety strategies in places such as nursing homes. See also *Carpentered environments *Geometrical-optical illusions References External links *Vertical–horizontal illusion (Wikiversity tutorial) Category:Optical illusions Category:Optical illusions